refactor(aqua): parse tool options locally

[risu729]

Depends on merged #9838. This branch has been rebased onto current main, so the PR diff is now only the Aqua typed-parser follow-up.

Summary

• Add a private AquaOptions wrapper for Aqua backend option reads.
• Move symlink_bins, Aqua vars, and lockfile option collection behind that wrapper.
• Keep behavior unchanged; this only follows the typed-parser direction from refactor(backend): parse tool options per backend #9838.

Verification

• cargo fmt --all -- --check
• git diff --check upstream/main...HEAD

This PR was generated by an AI coding assistant.

[greptile-apps]

Greptile Summary

This PR extracts Aqua-specific option parsing into a new AquaOptions<'a> wrapper struct, following the typed-options pattern introduced in the parent PR. No logic is changed — the three moved functions (symlink_bins, var, lockfile_options) are textually identical to the originals.

• AquaOptions::symlink_bins replaces the old AquaBackend::symlink_bins method, delegating to the new BackendOptions::bool helper which behaves identically to the original get_string(...).is_some_and(|v| v == "true" || v == "1") (the only difference is is_truthy adds a .trim() call, which is strictly more lenient).
• AquaOptions::var and AquaOptions::lockfile_options are verbatim lifts of the former free function aqua_var_option and the static method AquaBackend::lockfile_options.
• apply_var_options now takes &AquaOptions<'_> instead of &ToolVersionOptions, and call sites are updated to construct an AquaOptions from the raw options before passing it in.

Confidence Score: 5/5

Pure structural refactor with no logic changes; all moved code is textually identical to the original, and the new bool helper in BackendOptions is a straightforward delegation.

Every moved function is a verbatim lift from its original location. The only net-new code is BackendOptions::bool, which is a one-liner composing two already-tested primitives (get_string + is_truthy). Test coverage tracks the refactored call sites and the existing test assertions remain unchanged.

No files require special attention.

Important Files Changed

Filename	Overview
src/backend/aqua.rs	Moves symlink_bins, var/aqua_var_option, and lockfile_options/insert_vars_lockfile_options from AquaBackend static methods and module-level functions into a new AquaOptions<'a> wrapper struct; logic is byte-for-byte identical to the original.
src/backend/options.rs	Adds a simple bool helper to BackendOptions that mirrors the existing platform_bool_for_target logic but without platform resolution, used by AquaOptions::symlink_bins.

_{Reviews (2): Last reviewed commit: "refactor(aqua): parse tool options local..." | Re-trigger Greptile}

[gemini-code-assist]

Code Review

This pull request introduces a centralized BackendOptions utility and backend-specific wrappers, AquaOptions and GitBackendOptions, to standardize the handling of tool configuration options. This refactoring enables consistent support for platform-specific overrides across different backends. Review feedback pointed out that the is_truthy helper is currently case-sensitive and suggested a more robust implementation using lowercase matching. Additionally, it was noted that the new implementation for no_app detection now correctly respects platform-specific settings, which represents a change in behavior from the previous implementation.